Parasites and Biliary stones

Relationship between opisthorchiasis and biliary stones ٩٧
Relationship between opisthorchiasis and biliary
stones
Humans acquire opisthorchiasis by eating raw fish containing
infective metacercariae. The flukes reside inside the small bile ducts and
gallbladder and do not undergo systemic migration. The flukes are
occasionally found in the pancreatic duct (Ming-gang et al., 1983). As in
C. sinensis the pathological changes include: Dilated bile ducts with
thickened walls; desquamation of bile duct epithelium followed by
proliferative hyperplasia, fibrosis and goblet cell metaplasia, and
development of cholangiocarcinoma (Upatham et al., 1985).
The pathological changes are more or less related to the intensity
and the duration of the infection, and are commonly seen in older patients
with a large number of flukes. The pathogenesis is due to the mechanical
irritation by the flukes and some toxic substances produced by them.
(Harinasuta et al., 1984).
There is a significant increase in the frequency of biliary sludge
seen in the gall bladder in heavy O. viverrini infections (Elkins et al.,
1990 and Mairiang et al., 1992). Eggs and worm fragments have been
observed in the nidus of gallstones and in sludge supporting the role of
the parasite in initiating cholelithiasis (Riganti et al., 1988). Opisthorchis
infection is associated with several hepatobiliary diseases including
cholangitis, obstructive jaundice, hepatomegaly, cholecystitis and
cholelithiasis (Sripa, 2003).
The histochemical findings on the calcium and bilirubin coatings on
the opsithorchiasis eggs support this hypothesis. The presence of calcium
coating on the outer surface of the parasite eggshell suggests that the eggs
may act as a nucleus for stone formation. This may be similar to